Fractures of the proximal femur, especially those of the neck region are notoriously difficult to treat successfully partly because of poor circulation of blood to the head and neck. Lag screws inserted across the fracture into the head of the femur are widely used to immobilize the break to permit healing. The trailing end of the screw is usually supported by the tubular extension of a cortical side plate through which the nail can slide when some shortening of the neck takes place during healing. Often, instead of a side plate, an intramedullary rod with a transverse opening through which the nail can slide is used.
Because the fracture will be more stabilized if the broken ends are compressed together, particularly high neck fractures, screw devices that pull the base of the screw through the tubular support towards the side plate have been devised. While this also helps prevent harmful rotation of the bone ends on each other, a large number of devices have been devised to further prevent this rotation, such as keys and keyways in the tubular support. One of the problems with this approach is that it is difficult to correlate the rotation of the screw or nail with the optimal rotational position of the barrel and its side plate, especially if a device such as a nail with tangs has already been deployed.
While some devices have met some of these requirements, many have not. It is the aim of this invention to provide an easy to use and easy to manufacture apparatus that supports the trailing end of a fixing device, either a lag screw or a nail with locking tangs and enables initial compression of the bone ends together and continued compression while the fixing device is enabled to slide laterally, while at the same time, prevented from rotating.